Universal backlash prevention device



SePt- 7, 1943- E w. MKlNNEY 2,328,732

UNIVERSAL BACKLASH PREVENWI'IOH'` DEVICE TOP g IN V EN TOR.

Sept 7,1943 E. w. MQKINNEY i, 2,328,732

UNIVERSAL BACKLASH PREVENTON DEVICE Filed Dec. 2, 1942 2`sneets-sneet 2 F. V /al along the line8-81of Figure?.

Patented Sept. 7, 1943v My linvention. relates in general Yto vthe preven- "tionjof lost .motion between/two elements ,of l mechanism and more particularly to fthe `preven :Lt-ion of backlash abeitweena threaded element and -`a. threaded member threadably engaging each other, regardless of the position .of thethanfea-,ded

element and the athreaded member.

,An iobject ofgmyfinvent-ion is the provision an arrangement for preventing backlash-betw-een a threaded element and :a threaded `.merrlber 1,

ithreadably engaging each other, Whereinftheiarrangement is operativein any and all positions of the threaded element and the threaded lmerri- The present invention fis an improvement over my, invention shown, Adescribed 'and claimed in my pending `patent yapplication led,` June :12,

.1941, Serial No. 397,825 yfor Backlashgprevention device, the principal :featureof the improvement residing in the `factthat the presentwinvention may be used in any iand al1 positions. To ,this end, the present invention :maybereferredfto as a ,universal backlash Aprevention device.

Other objects and a fuller understanding ofk my inventionmay beha-dby referring to the rfol- `lowinggdescription and claims, taken in conjunction nwith Vthe Haccompanying drawings, `in which:

- 'Figure .1 representsia side, longitudinal,V crosssectional View of amechanism embodying :the "features of myinvention;

Figure 2 is an end cross-sectional 4view;ta1f;`en along theline 2-2f-of Figure 1;

einer" threads A @ranged tefpretent 1this :baehlash for any .and 'all :positions of ytbefthreaded parte;

" f With ref erease seither-.drawings Iillustrate -invention fin leermestierl Awith fa mechanism edm- -:arising .a statrenale'` ,emberfer support 1:0 .-.whiehis slidably :mea ed aa mevable element tl arranged tov be actuated by a cra'nklgl@ .meansp a sorewV thread lengagem nt. .The

,ce-within .the movable-mem- ;berfm. y llewsleevedisfa threaded mem-ber I 4 ,wniy is secured to ,the hollow `,sleeve by fmeansnf a key wedge p L@ (and ,a locking .key A9 'eh fts in a A,10.neftlljclinal key Luray-2.0. illustrated, a threaded element 116 threadably engages :the threaded lmembefll .zandrlis .arranged -to be :longitudinally .moved as .the threaded member (Mis rQtated-'bythecrank vL2.; ,The .right-hand fend .df the threaded elmentil is Vprovided with a :headilJlwl-iioh `may :bez-secured@ ,thefmovable member .Il Y,by.Irxeaxis v'Figure 3 is a view taken along thelinei-:Sfof

Figure `'2; L

4l'gure 4 isa development shown in the-nat, il-

lustrating the novel features `of ,myVi-nvention;

Figurei is a verysimilar to Figurea;

. vFigure 6 isagfragmentaryacross-sectionalview showing a modied formof the invention;

Figure 7 shows anothenmodied formof 'the invention; and

Figure,8 shows a ,cross-sectional' View `.ta-lien In a large number of mechanisms, `a mOi/'able Apart or object .is arranged toghe moved withreference to a station-ary support by means of ja threaded element operated by a Ycrank or `.hand wheel. :In order itoprovide `for the -free .turning `ofnthe"threadedelement,there isa slight clearlancebetweenqthe threadsof the threaded element andthe threaded member ,in which the .threaded element engages. j-,This small clearance resultsfin backlash between the two threaded parts. .-Ihatjisto say,;oneofthe threaded parts has to move-beforefeommunicatingits `motion .member `.t4 .and threadably erlsae'inl;A hethreaded element I6. The floating device's213 fisnQn-rotativelyseeuredmo the hollowsleeve 113 .by means ,of e lvioelsilis key. 2.4 .which slilably .engages .the .key Wav all. Accordingly. the floating ,threaded ment `,w th respectto the threaded, element 14.

As illustrated in Figur-'es "1 and .3.,Ltfhe adiaeent lends ef 1,the t "eaiied member' lill ,and the ea ,ing threaded devise 2;3 are 4respectively'provided easily, 4the adjacent .endso'f theifioatingthreaded devise 2 3 vand the threaded member fll'havei` a y5.0 i.plurality of pairs of vangularly disposed surfaces 5m,y and 3l whih 'denne 4converging 'adjacent surfaces betweenw'hichafball` 2'8 is located tenonstrain ``the floating v,threaded Vdevice 23 and 'the threaded member L4. apart la n 'd,againstthe oppoto 55 shitejsieegsor'vfaces ofthe threadsof 'the threaded eartinvention is element I6. As shownk in Figure 2, the pairs of converging adjacent surfaces 30 and 3l are arranged annularly about the threaded element I6. In the present invention, the pair of converging adjacent surfaces around the threaded element I6 is disposed to have at least one adjacent side surface arranged at a downward angle with respect tothe horizontal regardless of thejposition of the floating threaded device 23 and the thread- Y ed member I4. In this manner, my present in vention is universally adaptable for any one ofv A cover band `21 isi positioned externally of the wedging rings 25 and 26 to keepA many positions.

the ball from escaping.

In Figure 4 I have shown a developmentfofthe.. wedging rings 25 and 26 and in this development the wedging rings 25 and 26 have their axesY ar-v ranged in a horizontal position' as shown inFigures l, 2 and 3. The center of the Figure 4 represents the bottom and the two ends represent .the top of the wedgingring 'and the directionrof 'gravity istowards the bottom asindicated by the arrow line. v As illustrated, the two balls A' and B are vacting to separate the two wedging rings 'and 26, whichurges the floating threaded device '23 and the threaded member I4 against the oppositeside surfaces of the threads of the threaded felement II.Vv

In Figure 5 `I show a development Very -much VV.the samer as Figure 4 except that the axis of the uwedging rings 25 and 26 is vertical instead of horilzontal.V Consequently,"in Figure 5 the force. of

gravity Vis downward as indicated by the` arrow line andtheballs B, C, and D are urgedrtowards Vthe converging ends 'of the adjacently spaced surfaces.V `'Ihe lsprings 29 between-the wedging rings 25 and 264are arranged to support the floating threaded device 23 against gravity when the axis ofthe wedging rings-25 and 28 isvertical. `Ino'ther words,- the springs 29 are made suf- `iiciently'strong to support the floating threaded device 23 against-gravity which enables the balls to' be urged toward the converging end of the'V anwedgingv action o f the' balls between the adjacent surfaces issuchthat they'do not cause any Jamming of the threads of the threaded element -lII Iwithin theiloating threaded device 23 andthe threaded member I4. y l 'j'acently disposed surfaces may be relatively small,

Thev angle between-the ad- 'as illustrated.

' In Figure 6l I illustrate my invention with a nony, rotating nut '35v and .a iloating threaded'devi'ce 36 which is constrained against turning by a pin 31.

In 'Figure 6 Vthe threaded element I6 is turned which is just the'reverse from the showing 1n ,l Figure l where the threaded member I4 is turned.

The embodiment in Figure 6 employs the same "we'dging rings25 and 26 and the same balls'28r-as that shown with reference 'to Figures 1, 2 andl 3. The right-'handend of the pin 3l may be pressed forV otherwise secured within the non-rotating nut '35anfd the left-hand end of thepin is arranged `so that the lioating threadeddevice 36 may'move longitudinally with respect to' the non-rotating nut as. j e y y vIn Figures land 8'I show a modiiied engagement of my invention in that the ballsZBQarear- 'ranged inA vertical grooves Iin the wedgingrings rthe threaded element. Y y e 2. An arrangement for preVentingbacklaSh be,-

a spring cap 42 may be placed in the hollow sleeve I3 to hold the spring in place. The springs 4I Icontact the ball to oppose gravity. to insure that 'the balls are urged toward the*Y converging end of the converging surfaces.v In Figures l, 2 and 3 the springs 29 support the floating threaded de.

vice 23 to oppose gravity to insure that the balls areurged toward the converging end of the converging surfaces, whereas in Figures 7 and 8 thev springs 4I contact the balls for accomplishing the same purpose. The force of the springs 29 in .Figures V1`,2 frand 3 `and the force of the springs 4I in Figures 'I and 8 is notl sufcient to jam the 'i threads of the threaded element I6 within the floating threaded device and the threaded member. Regardless of the environment or the positionl of my backlash preventionf device, it .functions to prevent lost motion upon the turning of fthe threads. v In the drawings, I have illustrated the use. of

the balls 28 for separating the wedging rings, but it is to be understoodrthat rollers, wedges or any other device may be employed, and in theclaims AI have designated these devices as gravity iniluenced mass means.

The bearing 2I in Figure'l inf actual manufacture would" preferably be 4a two-way thrustr roller bearing so as to be completely free of en play while at the lsame time turn easily, Although I have described my invention with a certain degree of parti'cularity,`it is understood that the `present disclosure has been made only by way of example and that numerouschange's in the details of construction! and the combination and arrangement of parts 'may-be resorted'to without departing fromlthe' spirit 'and the'scope of the invention as hereinafter claimed. I claim as my invention: I L l. An arrangement for preventing `backlashbetween a threaded element anda threaded member threadably engaging 'e'achother comprising, in combination, a iioatirig lthreaded -device spaced from the threaded member and threadably engaging the threaded element, means. to constrain the floating threaded-*device in substantially a fixed angular relation withV respect to the threaded member to keepV the space between adjacent ends of the floating threaded'device'fand:thethreaded member substantially constant,the adjacentends of the floating threaded device and thethreaded member havinga plurality of pairs-of angularly disposed surfaces defining` converging adjacent surfaces, and gravity influenced mass means engaging the converging adjacent' surfaces of each,

said pair 'to constrain the floating threadeddevice and the threaded'mmberfapart and against the opposite side surfaces of thethre'ads' vof the threaded element, said pairs of'converging adjacent surfaces being! arranged annularlyabout tween a threaded element and a threadedmember threadably l engaging. each other, comprising, in combination,- a floating threaded 'device spaced vfrom the threaded member andthreadably'en- V gaging the threaded element, means lto? constrain adjacent ends of the floating threaded device and the threaded member having a plurality of pairs of angularly disposed surfaces defining converging adjacent surfaces, and gravity influenced mass means engaging the converging adjacent surfaces of each said pair to constrain the floating threaded device and the threaded member apart and against the opposite side surfaces of ythe threads of the threaded element, said pairs of converging adjacent surfaces being arranged around the threaded element and being disposed to have at least one pair of the diverging adjacent surfaces where the gravity influenced mass means is urged toward the converging end thereof regardless of the position of the floating threaded device and the threaded member.

3. An arrangement :for preventing backlash between a threaded element and a threaded member threadably engaging each other comprising, in combination, a floating threaded device spaced from the threaded member and threadably engaging thethreaded element, means to constrain the floating threaded device in substantially a xed angular relation with respect to the threaded member to keep the space between adjacent ends of the floating threaded device and the threaded member substantially constant, the adjacent ends of the floating threaded device and the threaded member having a plurality of pairs of angularly disposed surfaces defining converging adjacent surfaces, and gravity influenced mass means engaging the converging adjacent surfaces of each said pair to constrain the floating threaded device and the threaded member apart and against the opposite side surfaces of the threads of the threaded element, said pairs of converging adjacent surfaces being arranged around the threaded element and being disposed to have at least one adjacent side surface arranged at a downward angle with respect to the horizontal regardless of the position of the floating threaded device and the threaded member.

d. An arrangement for preventing backlash between a threaded element and a threaded member threadably engaging each other comprising, in combination, a floating threaded device spaced from the threaded member and `threadably engaging the threaded element, means to constrain the floating threaded device in substantially a fixed angular relation with respect to the threaded member tokeep the space between acljacent ends of the floating threaded device and the threaded member substantially constant, the adjacent ends of the floating threaded device and the threaded member having a plurality of pairs of angularly disposed surfaces defining converging adjacent surfaces, and ball means engaging the converging adjacent surfaces of each said pair to constrain the floating threaded device and the threaded member apart and against the opposite side surfaces of the threads of the threaded element, said pairs of converging adjacent surfaces being arranged around the threaded element and bein-g disposed to have at least one adjacent side surface arranged at a downward angle With respect to the horizontal regardless of the positionof the floating threaded device and the threaded member.

5. An arrangement for preventing backlash between a threaded element and a threaded member threadably engaging each other comprising, in combination, a floating threaded device spaced from the threaded member and threadably engaging the threaded element, means to constrain the floating threaded device in substantially a fixed angular relation with respect to the threaded member to keep the space between adjacent ends of the floating threaded device and the threaded member substantially constant, the adjacent ends of the floatingv threaded device and the threaded member having a plurality of pairs of angularly disposed surfaces defining converging adjacent surfaces, and gravity influenced mass means engaging the converging adjacent surfaces ofeach said pair to constrain the floating threaded device and the threaded member apart and against the opposite side surfaces of the threads of the threaded element, said pairs of converging adjacent surfaces being arranged around the threaded element and being disposed tc have at least one adjacent side surface arranged at a downward angle with respect to the horizontal regardless of the position of the floating threaded device and the threaded member, and spring means between the floating threaded device and the threaded member to support the floating threaded device against gravity.

6. An arrangement for preventing backlash between a threaded element vand a threaded meme ber threadably engaging each other comprising, in combination, a floating threaded device spaced from the threaded member and threadably engaging the threaded element, means to constrain the floating threaded device in substantially a fixed angular relation with respect to the threaded member to keep the space between adjacent ends of the floating threaded device and the threaded member substantially constant, the adjacent ends of the floating threaded device and the threaded member having a plurality of pairs of angularly disposed surfaces defining coni -verging adjacent surfaces, gravity influenced massrneans engaging the converging adjacent surfaces of each said pair to constrain the floating threaded device and the threaded member apart and against the opposite side surfaces Aof the threads of the threaded element, and spring means to oppose gravity to insure that the gravity influenced mass means is urged toward the converging end of the converging surfaces.

7. An arrangement for preventing backlash be tween a threaded element and a threaded member threadably engaging each other comprising, in combination, a oatingthreaded device spaced from the threaded member and threadably engaging the threaded element, means to constrain the floating threaded device in substantially a ilXed angular relation with respect to the threaded `member to keep the space between adjacent ends of the floating threaded device and the threaded member substantially constant, the adjacent ends of the floating threaded device and the threaded member having a plurality of pairs of angularly disposed surfaces defining converging adjacent surfaces, gravity influenced mass means engaging the converging adjacent surfaces of each said pair toconstrain the floating threaded device and the threaded member apart and against the opposite side surfaces of the threads of the threaded element, and spring means contacting the gravity influenced mass means to oppose gravity to insure that the gravity influenced mass means is urged toward the converging end ofthe converging surfaces.

ELSMERE W. MCKINNEY. 

